1. Field of the Invention
The present invention relates to a storage device and a control method therefor and, more specifically, is suitable when it is applied to a storage device storing data utilizing virtual volumes, and a method for controlling such a storage device.
2. Description of the Related Art
With a well-known technology for a storage system, virtual volumes consuming no physical storage area are defined, these virtual volumes are provided to a server, and allocation of the physical storage areas is performed at the time of actual data writing from the server, thereby increasing the use efficiency of the storage capacity of a storage device.
In another type of storage system, for increasing the use efficiency, any pools corresponding to virtual volumes are dynamically increased in storage capacity. For the purpose, a host computer monitors logical block address of a read or write I/O (Input/Output) for accessing logical volumes of a storage device, and based on any acquired logical block, the storage area of the logical volumes is dynamically extended. An example includes Patent Document 1 (JP-A-2003-15915). In still another type of storage system, the power needed for storage resources allocated to pools is reduced, and the storage resources are prevented from being reduced in life. An example includes Patent Document 2 (JP-A-2007-293442).